This invention relates to a targeting apparatus for use in performing transfemoral osteotomy. In this surgical technique the femur is exposed along a proximal-distal line, the soft tissue (skin, muscle) being folded back on each side to expose the bone. The proximal end of the femur is now opened as a xe2x80x9cwindowxe2x80x9d and a femoral prosthesis is inserted into the bone canal.
The technique requires careful pre-operative planning, usually from X-rays and it is possible to calculate in advance how far to cut the xe2x80x9cwindowxe2x80x9d so that the distal edge of the xe2x80x9cwindowxe2x80x9d end can become a datum base.
There are obvious difficulties in assessing the particular angular position of the prosthesis in the femoral canal and the exact location of the resectioning of the femur must be accurately judged. A further difficulty arises with regard to the placement of one or more retaining bolts towards the distal end of the stem of the prosthesis. These bolts or pins pass through the bone, the stem of the prosthesis and out through the other side of the bone thus anchoring the prosthesis in position. It is difficult for surgeons to judge the exact position to drill the holes in the bone to coincide with the holes in the implant and it is also necessary to select the correct angular position for the prosthesis and therefore the holes. It is also difficult to judge the exact distance down the femur for the holes to achieve the correct leg length of the correction.
The present invention is intended to overcome some of the difficulties referred to above and provide apparatus which provides a more accurate surgical technique.
According to the present invention, targeting apparatus for use in performing transfemoral osteotomy surgery comprises a support element provided with a drill guide, a connector for securing the support element to a prosthesis to be implanted, and to a resectioned femur, and a device for adjusting the angular position of the drill guide in relation to the resectioned femur about a proximal-distal axis.
Thus, the apparatus can be used to accurately locate the angular position of the drill guide and the prosthesis (anteversion setting) which can be used to drill the holes to take the retaining bolt or bolts in the bone. Preferably the support element includes means for connection to the proximal end of the femoral prosthesis. An indicator can be provided to indicate the angular position of the drill guide relative to the resectioned femur.
Thus, after careful X-ray examination the precise anteversion setting can be decided and this can then be transferred to the apparatus thus ensuring the correct angular position.
The apparatus can also include a device for adjusting the support element to accommodate alternative leg lengths. In order to do this an adjusting device can be included to vary the proximal-distal position of the support element in relation to the prosthesis securing means.
Once again, the necessary dimensions and requirements can be taken from X-rays and preset on the apparatus. With this arrangement the drill guide can be located at a predetermined proximal-distal position from the connector to the proximal end of the femoral prosthesis.
A locator can be included for locating the drill guide in alternative proximal-distal positions on the support element thus the apparatus can be adapted for prostheses with holes in different positions and two or more drill guides can be provided.
The connector for securing the support element to the resectioned femur is preferably in the form of an adjustable open jawed clamp adapted to partially surround the femur with which it is to be used.
A guide can be included for locating the support element on the resectioned proximal end of the femur and these guide means can be carried on the femur connector.
The support element can be in the form of an L-shaped frame, one arm of which carries the drill guide and the femur securing means and the other arm carrying the connector for connection to the femoral prosthesis which is to be implanted.
With this arrangement the femur connector can be connected to the L-shaped frame by a bracket which can be adjusted in proximal-distal directions on the frame and in relation to which the femur connector can be angularly adjusted about a proximal-distal axis.
In a preferred embodiment the bracket is readily removable from the L-shaped frame.
The femur connector can include a device for adjusting and clamping the connector according to the femur diameter.
In another preferred embodiment the connector for securing the support element to the resectioned femur includes a universal joint.